Carbohydrate antigens of embryonal carcinoma cells: changes upon differentiation

Embryonal carcinoma (EC) cells, the malignant stem cells of teratocarcinomas, resemble early embryonic cells morphologically, developmentally, and with respect to several cell surface characteristics. EC cells often differentiate into a variety of cell types when treated with chemical agents such as retinoic acid, or when placed in a normal embryonic environment. Developmentally regulated surface antigens of EC cells and their differentiated derivatives have been defined using monoclonal antibodies. Many of these "differentiation antigens" have proved to be oligosaccharide chains carried on membrane glycolipids and/or glycoproteins. Our analyses of glycolipid composition in a pluripotent human EC cell line, NTERA-2, have revealed a complex set of glycoslylation changes that occur during cellular differentiation. Like early embryos, undifferentiated NTERA-2 EC cells express predominantly globo-series glycolipids. However, once differentiation is initiated by addition of retinoic acid there is a marked shift of cellular glycolipids from globo-series to lacto- and ganglio-series. Distinct subsets of differentiated cells are characterized by their expression of different patterns of glycolipid antigens. These changes in cell surface phenotype may serve to mark cellular identity and facilitate morphogenetic cell interactions during embryonic development.